Air pressure control means



Oct. 23, 1934. 1, T, NEEDHAM 1,977,737

AIR PRESSURE CONTROL MEANS Filed Aug. 27, 1932 2 Sheets-Sheet l v o 1h,/11 5 14 l,

4? 4f- III ,-fy 4Z. 46 44 i; 'l il I l: l i 'L i l U 1 l M QL-k 43 1 i-"lb 50 INVENTOR JOHN T. NEEDHAM ATTORNEYS UCL 23, 1934. J' Tl NEEDHAM I1,977,737'

AIR PRESSURE CONTROL MEANS Filed Aug. 27, 1932 2 Sheets-Sheet 2 i 3/ i;/HHHQw/Ul nia 76 37 0'? g? 3g )a 7% 1.5 E 5 INVNTOR JOHN T. NEEDHAMATTORN EYS Patented Oct. 23, 1934 i UNITED- sTATEs PATENT oFFicEAIRPREssURE CONTROL MEANS John T. Needham, North Plainnela, N. J.Application August 27, 1932, serial4 No. 30,672 9 claims. (c1. 23o- 12)An important object of the presentinvention is into a terminal 10. If anumber of the tubes are to provide, in a pneumatic dispatch tube system,in service simultaneously there will be a decided thoroughly practicaland efiicient means to govern drop in pressure in the manifold 3 and areducautomatically the operationof the blower or air tion of the vacuumin the manifold vunless `the 5 pump of the system in accordance with the`varyspeed of the blower is increased. Consequently 60 ing servicerequirements of the system. the carrier transmission speed will bermaterially Other objects of the invention will appear here'- reduced. Inorder toQprovide adequate pressure inafterl and suction for rapidcarrier` transmission regard- In the drawings, Fig. 1 is a perspectiveview of less of thenumber of tubes in service, I have pro- 10 the blowerof a pneumaticdispatch tube system, vided a pneumatically operabledevice to auto- 65 an electric motor for driving the blower and thematically control the speed of the motor in accordcontrol device toautomatically control the speed ance with the `service requirements ofthe system. 0f the motor; This deviceis operable in response to changesin Fig. 2 a sectional plan View of the blower air pressure in the systemto speed up or slow down and the piping which connects the inlet andoutthe motor as the number `of tubes in service in- 70 let of the blowerwith the motor speed control 4creases or decreases. l. device; y l Theblower 13 is of the standard type. It has Fig. 8 a vertical sectionalView of the motor cooperating rotary impellers 17 in a compression speedcontrol device; and f chamber 18 in communication with the inlet 15 20Fig. 4 a diagrammatic View of a pneumatic and the outlet 12. Eachvimpeller. is fixed to a 75 dispatch tube system and including theblower, the shaft 19 and the shaft has -a gear 20 xed to it motor andtheautomatic motor speed control debelow the compression chamber. Bothgears are vice. A driven by a worm21 fixed to a drivev shaft 22.

In order to make clear the purpose of the inven- The shaft 23 of themotor 16 has a direct drive 25 tion, as employed in a pneumatic dispatchtube connection with the drive shaft 22 of the blower. 8O system, thedispatch tube system shown in Fig. 4 The outlet and inlet of v theblower have elbow will rst be generally described. The system is pipeunions 24 to which the large pressure and one in which the invention maybe employed Very suction pipes 11 and 14 respectively are joined.advantageously. It may, however, be employed The electric motor 16 is amotor known com- 36 in other connections also. The system showninmercially as a brush-shifting motortype BTA. 85

cludes a main sending terminal unit 1 and a main Such a -motor has itscommutator brushes supreceiving terminal unit 2. Unit 1 includes an airported in a rotatable mounting enabling the pressure manifold 3 and anumber 0f Sending terbrushes. to be shifted around the commutator minals4. Unit 2 includes an air Ysuction-or vacaxis to varyy the speed of themotor. Ordinarily uummanifold 5 and a number of discharge terythe brushmounting is rotated by means of a 90 minals 6. From the sendingterminals 4 outgoing hand lever or by means of a small pilot motor todispatch tube lines 7 lead to discharge terminals change the speed .ofthe main motor. In the 8 at outlying stations. Return dispatch tubelines vpresent case my automatic speed control device 9 lead from theoutgoing lines 5 at said stations effects theshifting of the commutatorbrushes to 40 to the discharge termlllS 6 0f the receiving unit adjustthe motor speed in accordance with the 95A and communicate with thevacuum manifold 5. `pneumatic requirements of the tube system.

Each return tube line has a sending terminal 10. Thekautomaticspeedcontrol device includes a The pressure manifold 3 is Supplied Withair under pair of vertical cylinders 25 and 26 open at their pressurethrough alargepipell leading from the upper ends and closed at theirlower ends and outlet 12 of a, blOWel 01 air pump 13. From the supportedby a base 2'7. In the present instance 100 vacuum manifold 5 a largesuction pipe 14 leads to a single casting forms the base and cylinders;

the inlet 15 of the blower or pump. The latter lsaid parts maybe formedseparately, however.

is driven byan electric motor 16. A i A piston or plunger 28 is tted forvertical recip- When a carrier is inserted into any one of the rocationin cylinder. 25 and a piston or plunger sending terminals fortransmission the tube con- 29 is fitted for vertical reciprocation` inthe cyl- 105 nected to the'terminal is opened to the pressure inder 26.Disposed over the upper ends of the manifold 3 and, by means 110iShOWIl, the concylindersin anV intermediate position is a pulley nected.return tube 9 is simultaneously opened to 30. This pulley is fixed `to ashaft 31 one end the vacuum manifold5. These tubes are also ofwhichissupported by a bearing bracket32 atopened to the manifoldswhenacarrier isinserted tached to the cylinders.` The opposite end of1,10

the shaft is supported by a bearing borne by the motor structure and isoperatively connected to the rotatable mounting of the commutatorbrushes. This shaft replaces a short shaft to which either a hand leveror a pilot motor is ordinarily connected. The operative connectionbetween the shaft and the brush mounting is a conventional part of themotor and it is thought to be unnecessary to illustrate it. Theplunger'28 has an eye 33 at its upper side and the plunger 29 has anupwardly extending stem 34 provided with an eye 35 at its upper end. Aflexible tension strand or cable 36 is trained over the pulley and hasits ends anchored to said eyes. On the stem 34 is a plurality of weightdisks`37 radially slotted to permit their removal'from the stem. Theseweights rest upon the plunger 29.

The lower portion of cylinder 25 and its plunger 28 define a suction orvacuum chamber 38 andv the lower portion of cylinder 26 and its plunger29 dene a pressure chamber 39. Chamber 38 has a port 40 and chamber 39has a port 41. From the elbow 24 of the blower inlet a small suctionpipe 42 leads to the port 40 of said vacuum chamber and from the elbowof the blower outlet a small pressure pipe 43 leads to the port '41 ofsaid pressure chamber. Each of said pipes has a valve 44 to adjust itscapacity.

The automatic speed control device operates as follows in conjunctionwith the dispatch Atube system: The pipes 11 and 43 place the vpressuremanifold 3 of the system'in constant communication with the pressurechamber 39 of the control device so that substantially the same pressurewill exist in said chamber as in the manifold. Similarly, the pipes 14and 42 place the vacuum manifold 5 of the system in constantcommunication with the vacuum chamber 38v ofthe control device, so thatsubstantially the same degree of vacuum will exist in both themanifoldand chamber. Ordinarily one or a small number of the tubes l and9 will be kept constantly open tothe manifolds 3 and 5 respectively.`The blowerv may be kept running at a slow speed to keep a certaindesired degree of pressure in the manifold 3 and vacuum in the manifold5. This normal vor idle pressure and vacuum are determined by theweights .3T of the control device. By changing the number or Vsize ofthe weights the normal position of the commutator brushes may be varied.

' Thereby the speed of the motor is adjusted to obtain the desirednormal pressure and vacuum.

When additional dispatch tubes are placed in operation there will be adrop in pressure in the manifold 3 and in the connected pressurevchamber 39 of the control device. The weighted plunger 29 will then movedownward to rotate the pulley 30 and shaft 31 clockwise, with refervenceto Figs. 1 and 3, and cause the-commutator Ybrushes to be shifted toincrease the speedof the to move upward.' "An increase in pressure inchamberV 39 is accompanied by an increase of vacuum in chamber 38 andatmospheric pressure on top of piston 28 forces it down vto rotate theshaft'31 counter-'clockwise and shift the commutator brushes to slowdown the motor.

The control device is sensitive and responsive to pneumatic fluctuationsin the system and operates to automatically govern the speed of themotor in accordance with the widely varying pneumatic requirements ofthe system. Rapid transmission of the carriers is obtained regardless ofthe number of dispatch tubes in simultaneous operation.

' The motor speed control device is responsive to pressure and vacuumacting together and it constitutes a very sensitive and flexible meansfor quickly and nicely adjusting the speed of a motor through manygradations, in accurate accordance with varying service demands upon themotor.

What I'claim is:

1. In a fluid pressure developing apparatus including a pump, anelectric motor operatively connected to said pump and having commutatorbrush means shiftable to change the speed of the motor; a fluid pressureoperated control device to shift the commutator brush means comprisingan upright cylinder, a weighted plunger in said cylinder, the cylinderand plunger defining a fluid pressure chamber beneath the plunger, anoperative connection between the plunger and the commutator brush means;and a fluid pressure connection between the fluid pressure developingapparatus and said fluid pressure chamber, to cause the shifting of theplunger and brush means in response to Variations in the fluid pressurein the apparatus.

2, In a fluid pressure developing apparatus including a pump, anelectric motor operatively connected to said pump and having commutatorbrush means shiftable to change the speed of the motor; and a fluidpressure operated control device to s'hift the commutator brush meanscomprising an upright cylinder, a VWeighted plunger in said cylinder,the cylinder and plunger defining a fluid pressure chamber beneath theplunger, an operative connection between the plunger and the commutatorbrush means, a fluid pressure connection between the fluid pressuredeveloping f apparatus and said fluid pressure chamber, toy cause theshifting of the plunger and brush* means in response to variations inthe fluid pressure in the apparatus, and means loo for varyingthe weightof the said weighted plunger to vary the normal position of said brushmeans.

3. A fluid pressure developing apparatus including a pump; an electricmotor operatively connectedto said pump and having commutator brushmeans shiftable to change the speed of i the motor; and a fluid pressureoperated control device operatively connected to said brush means toshift' same and including a pressure chamber and a vacuum chamber, meansin said chambersshiftable in response to variations in the degree ofpressure and in the degree of vacuum in said chambers, and meansoperatively connecting said pressure-vacuum responsive means to thebrush means to move said brush means in response to changes in thedegree of pressure and vacuum in said chambers.

' 4. A lluid pressure developing apparatus including a pump; anVelectric motor operatively vconnected to said pump and having commutatorbrush means shiftable to change the speed vof the motor; and a fluidpressure operated control device operatively connected to said brushmeans to shift `same and including a pressure chamber and a vacuumchamber, means in said chambers 'shiftable in response to variations'inthe degree of pressure and in the degree of vacuum in said chambers,means operatively connecting said pressureevacuum responsive means tothe brush means to move said brush means in response to changes in thedegree of pressure and vacuum in said chambers; and adjustable means tovary the relative normal positions of the pressure-vacuum responsivemeans to vary the normal position of the brush means to establish anydesired normal motor speed.

5. `A uid pressure developing apparatus including a pump; an electricmotor operatively connected to said pump and having commutator brushmeans shiftable to change the speed of the motor; and a fluid pressureoperated control device operatively connected to said brush means toshift same and including a pressure chamber and a vacuum chamber, meansin said chambers shiftable in response to variations in the degree ofpressure and in the degree of vacuum in said chambers, means operativelyconnecting said pressure-vacuum responsive means to the brush meanstomove said brush means in response to changes in the degree of pressureand vacuum in said chambers, and adjustable means to vary the normalposition of the pressure responsive means to vary the normal position ofthe brush means to establish any desired normal motor speed.

6. A fluid pressure developing apparatus including a pump; an electricmotor operatively connected to said pump and having commutator brushmeans shiftable to change the speed of the motor; and a fluid pressureoperated control device operatively connected to said brush means toshift same and including a. pressure chamber and a vacuum chamber, meansin said chambers shiftable in response to variations in the degree ofpressure and in the degree of vacuum in said chambers, means operativelyconnecting said pressure-vacuum responsive means to the brush means tomove said brush means in response to changes in the degree of pressureand vacuum in said chambers, and adjustable weights adapted to beapplied to the pressure responsive means to vary the normal position ofthe brush means to establish any desired normal motor speed.

7. In a fluid pressure developing apparatus including a pump and anelectric motor operatively connected to said pump and having commutatorbrush means shiftable to change the speed of the motor, a fiuid pressureoperated control device to shift said brush means comprising a pair ofupright cylinders, a plunger in each cylinder, one cylinder and theplunger therein defining a pressure chamber beneath the plunger and theother cylinder and the plunger therein defining a vacuum chamber beneaththe plunger, a fluid pressure connection between the pump outlet andsaid pressure chamber, a fluid suction connection -between the pumpinlet and said vacuum chamber, the plungers being operatively connectedto shift vertically in unison but in opposite directions in response tovariations in the degree of pressure in the pressure chamber andvariations in the degree of vacuum in the vacuum chamber, and anoperative connection between the plungers and the brush means to shiftthe latter, for the purpose set forth.

8. In a fluid pressure developing apparatus including a pump and anelectric motor operatively connected to said pump and having commutatorbrush means shiftable to change the speed o-f the motor, a fluidpressure operated control device to shift said brush means, comprising apair of upright cylinders, a plunger in each cylinder, one cylinder andthe plunger therein defining a pressure chamber beneath the plunger andthe other cylinder and the plunger therein defining a vacuum chamberbeneath the plunger, a uid pressure connection between the pump outletand said pressure chamber, a fluid suction connection between the pumpinlet and said vacuum chamber, the plungers being operatively connectedto shift vertically in unison but in opposite directions in response tovariations in the degree of pressure in the pressure chamber andvariations in the degrec of vacuum in the vacuum chamber, an operativeconnection between the plungers and the brush means to shift the latter,for the purpose set forth, and means to impose a constant yieldableresistance to upward shift of the compression chamber plunger, saidresistance means being adjustable to vary the resistance to plungershift.

9. In a fluid pressure developing apparatus including a pump and anelectric motor operatively connected to said pump and having commutatorbrush means shiftable to change the speed of the motor, a fluid pressureoperated control device to shift said brush means, comprising arotatable shaft operatively connected to said brush means to shift thelatter, a pulley Xed to said shaft, a pair of upright cylinders disposedbeneath said pulley, a plunger in each cylinder, one cylinder and itsplunger defining a fluid pressure chamber beneath the plunger and theother cylinder and its plunger defining a vacuum chamber beneath theplunger, a flexible tension strand attached at its opposite ends to saidplungers and trained over said pulley, a uid pressure connectionbetween' the pump outlet and said fluid pressure chamber, and a suctionconnection between the pump inlet and said vacuum chamber, to shift theplungers and thereby shift the brush means in response to changes inpressure and changes in vacuum in said chambers.

JOHN T. NEEDHAM.

